A Physically Unclonable Function (PUF) is a function based on electrical and physical characteristics of an integrated circuit that may be used to uniquely identify the integrated circuit. A PUF is determined based on responses (e.g., outputs) of an integrated circuit to challenges (e.g., inputs) provided to the integrated circuit. Integrated circuits have unique responses to challenges based on differences in the electrical and physical characteristics (e.g., variations in doping levels, resistances, capacitances, etc.) of the integrated circuits that result from the manufacturing processes of such circuits. These challenge-response pairs can be used to generate a PUF to uniquely identify a corresponding integrated circuit. Using a PUF as a unique identifier for an integrated circuit can be used to prevent attackers from easily cloning the circuit.